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8221568 
Book/Book Chapter 
Physical Properties of Iodine 
Kaiho, T 
2014 
Wiley Blackwell 
Iodine Chemistry and Applications 
9781118466292 
7-14 
English 
Iodine has a moderate vapor pressure at room temperature and in an open vessel slowly sublimes to a deep violet vapor that is irritating to the eyes, nose, and throat. This chapter tabulates the physical properties of iodine in solid, liquid and gas phases. Iodine dissolves easily in most organic solvents such as hexane, benzene, carbon tetrachloride, and chloroform owing to its lack of polarity, but it is only slightly soluble in water. However, the solubility of elemental iodine in water can be increased by the addition of sodium or potassium iodide. Iodine accepts electrons from the solvent molecule into its lowest unoccupied molecular orbital (LUMO). This lowers the energy of the transition from the highest occupied molecular orbital (HOMO) of the iodine atom to its LUMO, thereby changing the color from the characteristic violet to brown and other colors. The physical properties of the first four halogens are summarized. © 2015 by John Wiley & Sons, Inc. All rights reserved. 
Highest occupied molecular orbital (HOMO); Iodine atom; Lowest unoccupied molecular orbital (LUMO); Organic solvents; Solubility